Studies about active mode of active fault (2)

Tamura, Yoshiharu*; Kubouchi, Akihiko*; Muraoka, Akiko*

JNC TJ7420 2005-043, 225 Pages, 1998/02

JNC-TJ7420-2005-043.pdf:113.8MB

The purpose of this study is carried out to reveal detailed distribution of Senya active fault, and to obtain data with displacement (change of period and space) of fault active area and influential area of fault activity, a view of investigation to be possible of fault activity in the future and active area. The content of studies are aerial photographs and field survey to evaluate distribution activity of fault, and boring survey and radiocarbon dating to estimate an age of fault activity, and reflection method and gravity prospecting to reveal fault form in great depth. As a result of studies, Senya fault to happen earthquake in 1896 is confirmed to be thrust to the eastern at an angle to 20 degree and there is distributed pumice-tuff formed Neogene in hanging wall and conglomerate accumulated Quaternary in footwall. In addition, displacement rate of Senya fault is proved to be 0.94-1.4 millimeter per year with the use of the radiocarbon age of chips of wood in conglomerate that distribute in foot wall. On the other hand, Senya fault and Kawaguchi fault laid east of its fault indicate to great depth clearly, and there is possibility that these faults are connected with great depth. Namely, Senya fault is thought to shift from Kawaguchi fault, and the rate of movement is estimated 1.2 millimeter per year.